The development of increasingly large mobile construction cranes of the telescoping boom type has necessitated the use of correspondingly larger counterweights on the turntable mounted frame superstructure. These massive counterweights must be demounted in order to comply with highway maximum weight limitations and require transport on separate vehicles. It is also desirable at times to store the counterweight or place it on the ground. The mass of such a counterweight is so great that it requires the use of a large size crane to lift and manipulate it.
Accordingly, the objective of the present invention is to provide an improved structure for a very massive crane counterweight of the above-mentioned class and an improved more efficient method of handling the same. In achieving this objective, a power-operated raising and lowering means for the counterweight is built into the counterweight itself and therefore adds to the mass of the counterweight while rendering the structure compact.
The present invention is a radical departure from known prior art devices wherein the counterweight raising and lowering means are not self-contained in or on the counterweight but are a part of or on the crane superstructure. The self-contained power lifting means of the counterweight in accordance with the invention is not only more suitable for raising and lowering an extremely massive counterweight with stability, adequate guidance and safety but also contributes to the mass or weight, as stated.
Other features and advantages of the invention will become clearly apparent during the course of the following description.